Absorption refrigerating apparatus



Jan. 1, 1935.

D. B. KNIGHT 1,386,638

AsonP'rIoN REFRIGERATING APPARATUS Filed June 28. 1932 2 Sheets-Sheet 1 Oa w N l N Q :a a N C KN"- l w R fg Q n) "D Q n sa N Q C N l a Q l: D l 1 J u Q N EN K l l l l l l l l l I l v Q i L Y INVENTOR. VDa/v/'imB-[v/awr ATTORNEY.

Jan. l, 1935. D. B. KNIGHT ABSORPTION REFRIGERATING APPARATUS Filed June 28, 1932 2 Sheets-Sheet 2 INVENTOR. A Da/VHLDBK/v/GHT QWZ/ ATTORNEY.

Patented Jan. l, 1935 UNITED STA-'rss' f 1,986,638 v AnsonPTroN REFRIGERA'HNG APPARATUS Donald Branch Knight, Brooklyn, N. Y., assignor 'i to Electrolux Servel Corporation, Newl York, N. Y., a corporation of Delaware a Application June 2s, 1932, serial No. 619,620

2s claims- (c1, 62-119.5)

through conduit 16 into the rectifier casing 17 This invention relates to absorption refrigerating systems and more particularly to the control of such systems whereby a ,higher temperat'ure is temporarily obtained in the evaporator or cooling element at intervals for the purpose of allowing accumulated frost to melt, which is commonly known as defrosting. More specifically there is contemplated defrosting .control of continuous absorption refrigerating systems in which circulates an inert pressure equalizing gas.

This invention is particularly applicable to absorption refrigerating systems operated by heat supplied directly by combustion of fuel, as, for instance, by a gas burner. In accordance with this disclosure, a temporary higher temperature in the evaporator or cooling element is obtained by controlling the condition and rate of flow of fluids in the system which is accomplished by controlling the cooling of the heat rejecting portions of the system, as, for instance, the condenser.dh This may be accomplished in a water cooled machine by control of the water supply provided by a Water switch valve which may be manually or automatically operated or both.

' This method of defrosting control eliminates rduction of the burner flame and the attending disadvantages due to difficulty in adjustment' for minimum flame and wide variations in gas conditions which result in the flame blowing out and the nuisance to the user of relighting the burner.

Other objects and advantages will be apparent from the following description taken in connec-- tion with the accompanying drawings, in which Fig. 1 shows schematically an absorption refrigerating system of the pressure4 equalized type arranged for defrosting control in accordance with this invention;

Fig. 2 shows a system as in Fig. 1 with a modified arrangement'for defrosting control; and

Fig. 3 shows schematically, in vertical section,

'a semi-automatic water valve adapted for switching the cooling water-supply in system'sshown in the other figures. f

Referring to Fig. l of the drawings, a generator 10 adapted to contain a solution of refrigerant in an absorption liquid suchras ammonia in Water, is divided by,a partition 11 into an upper generating chamberI 12 and a lower pump chamber 13. Heat is supplied to the generator by a burner 14 in a flue 15 extending vertically through both chambers. Ammonia gas expelled from solution in the ge'neratm by heat passes` and then in series through condenser 18, pressure vessel 19, and condenser 20, as hereinafter more fully described. The lower condenser 20 is cooled during normal operation and the ammonia liqueies and fills the vent chamber 21; chamber 22, and ows through conduit 23 into the rectier casing 17. j

Liquid ammonia overows from the chamber 22 through conduit 24 into the top of the evaporator 25 where it flows downwardly over baille plates 26, evaporating into the-inert gas, hydrogen, which also enters the top oi.' the evaporator through conduit 27. The resulting heavier gas mixture of ammonia and hydrogen flows from the bottom of the evaporator 25 through conduit 28, gas heat exchanger 29, and conduit 30 to the lower part of the absorber 31. i

`Weak absorption liquid from the lower part of the generating chamber 12 flows through conduit 32, liquid heat exchanger 33, and conduit 34 into the upper part of absorber -31 where it ows downwardly over bale plates 35, labsorbing ammonia out of the gas mixture. Hydrogen, being lighter than the gas mixture, flows from the top of the absorber 31 through conduit 36, gas heat exchanger 29, and conduit 27 back to the Vup'per part of the evaporator. Enriched absorption liquid accumulates in the lower part of the absorber 31 from where it flows in conduit 37 through the liquidl heat exchanger 33 to chamber 13 from .where it is raised by thermosyphonic .action through conduit 38 back into the. gen-J erator chamber 12. Except for the condenser arrangement, this type of system is well known, in the art and for moredetailed explanation, reference may be had to Patent No. 1,609,334 to von Platen et al.

In refrigerating systems of this-type which are water' cooled, the cooling water is usually circulated rst through the absorber cooling coil 39- andthenthrough the condenser. 'Referring to Fig. 1 of the drawings, cooling water is circulated rst` through the absorber cooling coil 39 and then through conduit 40 to awater swltchvalve 0f this description, valve 41 ls intended to be shifted from its normal to defrosting position manually and returned to its normal position automatically by the thermostat 45 responsive to a p'redeterminedincrease in temperature of the evaporator 25. I

e During normal operation of the refrigerating system, cooling 'water ows only through the lower condenser 20 as previously described, and

ammonia gas iiowing from therectiiier casing 17 through the upper condenser 18, pressure chamber 19, and condenser 20 is condensed to-a liquid in the latter. TheI discharge end of the `condenser 20 is connected to the lower part of the vent chamber 2l, which, with chamber 22, conduit 23, and3rectier' casing 17, forms a liquid trap .which fills with liquid ammonia and seals off the discharge end of the condenser 20. During normal operation of the system, liquid stands toa level in the rectier casing 17 just below the opening in the upper end of conduit 16 from the generator. Liquidrises in vent chamber 21 and chamber 22, which form thegother leg of the liquid trap, and overiiows from chamber 22 through conduit 24 into the evaporator 25. Hydrogen is vented to the g'as system through the column of liquid in vent chamber 21 and cone duit 46 to the top of the evaporator 25.

When it is desired to defrostthe evaporatorJ or cooling element 25, the water switch valve 4l is operated -to cut Ioff the supply of water to the lower condenser 20, and deliver cooling water through conduit 47 to the upper condenser'l from where it flows to waste through conduit 48. When the cooling water is switched to the upper condenser 18, condensation occurs here instead of in the lower condenser 20 and the liquid columns in vent chamber 21 and chamber 22 fall due to the collapse of ammonia vapor in the upper condenser. The liquid level in the rectier casing 17 consequently rises above the opening of conduit 16 and the liquid flows back into the generator. As a result, no liquid ammonia is delivered to the evaporator, the temperature of "which rises-'ftp melt accumulated frost.

The operation of the refrigerating system 'however continues with ammonia gas being condensed in the upper condenser 18 and draining back tothe .gen-

erator by overow through'conduit 16.

The pressure vessel 19 provided with baffles 19a and located in the-circuit between the two condensers 18 and 20 performs two functions. First,

it provides a large quantity of ammonia vaporto be condensed when the cooling water is switched to the upper condenser thuse insuring the fall of the liquid columns in' chambers 21 and 22. Secondly, it provides for, accumulationof hydrogen v1n the condenser system which is not vented into the gasasysteniduring defrosting,"thus delaying the increase of vpressure in the condenser system so that it does not overbalance the pressure increase in the evaporator which accompanies the rise in temperature during defrosting.

When the evaporator reaches a predetermined high temperature, a thermostatic element 45 automatically returns tlie water switch valve 41 to its normal position, whereupon cooling water is again delivered to the lower condenser 20 andtemplated bythis invention. As previously described, ammonia gas from-the generator flowsl` lthrough conduit 16`into the rectifier casing 17.

The lower part of the rectifier casing is connected through an overflow conduit 49 to the upper part of the evaporator 25. The top of the rectifier casing 17 is connected to condenser 50, the other end of which is connected through conduit 51 to conduit 49. The rectifier casing 17 ,and conduit 49 form a liquid trap so that liquid ammonia from the condenser stands in the rectifier casing 17 aroundthe conduit 16 and overflows through conduit 49 into the evaporator. The condenser system is vented into the evaporator through an extension 52 of conduit 51. Cooling water from conduit /3 is directed by the water switch valve 54 through conduit 55, condenser 50, conduit 56, and to waste through conduit 57 provided with the usual control valve 58. The valve 54 may .be the samev as the valve 41 previously described in connection with Fig. 1. In this modification, a by-pass conduit59 is provided from the switch valve 54 tothe waste pipe 57 through control valve 58.

When it is desired to defrost the evaporator 25, the valve 54 is turned manually from its normal position to direct cooling water through the by-pass 59. Consequently ammonia vapor is no longer condensed in the condenser 50 and passes as warm vapor to the evaporator 25 through the vent pipe 52. y When the evaporator reaches a predetermined high temperature, a thermostat 60 operates automatically to return the valve 54 to its normal position; directing the cooling water back through the condenser, whereupon normal operation is resumed.

Reference has been made previously to a water switch valve which may be turned manually from a first position to a second position and returned automatically to its i'lrst position responsive to a predetermined increase in temperature of some part of the refrigerating system. Such a valve is illustrated schematically in Fig. 3 of the drawings. The valve casing 76 is divided by partitions 77 and 78 into two outer chambers 79 and 80 communicating with a central chamber 81 through valve openings 82 and 83 respectively. Cooling iiuid entering the central chamber 81 through conduit 84 is directed to either of the louter chambers 79 and 80 to which are connected conduits85 and 86 respectively. A valve operating rod 87 carries valve members 88 and 89 adapted to alternately open and close valve openings 82 -and 83 respectively when the valve `rod 87 is shifted between its upper and lower valve opening 83 to chamber 80 and' conduit 86..

v.The valve rod 87 is provided with a cam 92 adapted to be engaged by a corresponding ca m 93 on a push rod 94. -The latter is provided with a push button or handle 95 and is normally main- Cil tained in its disengaged position by a spring 96.

A thermal responsive disk or bi-metallic member 97 is carried by the lowerend of the valve rod 87. lThe element undergoing a change in temperature to which the operation of the valve is responsive is represented by the member 98.

When this valve is used for defrosting control to the right against the action of spring 96. The cam 93 on the push rod engaging the cam 92 on the valve rod 87 forcesthe latter downwardly, snapping the spring member 91 to its lower po- 70 as previously described, the push rod 94 is moved sition, as illustrated, and bringing the thermal responsive member 97 into thermal relation with the element 98. When the push rod is released, it returns under the, action of spring 96 to its inoperative positionY and the valve rod 87 is retained in its lowe'r position by the `spring member 91.

In this position, the valve opening 83 is closed and water is directed from conduit 84 and central chamber 91 through valve opening 82 into chamber 79 and conduit 85. When the element 98 reaches a predetermined temperature, the thermal responsive member 97 exes to the curved position indicated in dotted lines snapping the valve rod 87 back to its normal position in which valve opening 82 is closed and valve opening 83 opened. As the thermal responsive element 97 cools, it resumes its straight position indicated by the straight dotted line and the device is again ready for operation.

Obviously in thev construction of this valve the flexible disk 90 maybe replaced by `a stufhng box or exible bellows, and various snap acting devices such as spring tensioned toggles may be employed in place of the spring member 91 as well known in the art. Also instead of bringing the thermal responsive member 97 intodirect relation withthe element 98 an expansible fluid thermostat might be employed with the sensitive bulb attached to the element and the expansible member operatively associated with the valve rod 87, which is also well known in the art.

'.It will be obvious to those skilled in the art that various other changes may be made in the construction and arrangement without departing from the spirit of the linvention and therefore the invention is not limited to what is shown in the drawings and described in the specication but only as indicated in the following claims.

I claim: v

1. The method of refrigerating with a system having a cooling element and a heat rejecting portion which includes, continuing circulation of refrigerant fluid in the system, and temporarilyraising the temperature of the cooling element to melt accumulated frost by discontinuing'the removal of heat from the heat rejecting portion of thev system, and resuming the cooling of said portion responsive to rise in temperature of a portion of the system affected by said discontinuance of heat removal.

2. 'Ifhe method of refrigerating with a system having a cooling element and a water cooled condenser which includes, continuing circulation of refrigerant fluid in the system, and temporarily increasing the temperature of the cooling element to melt accumulated frost by discontinuing the supply of cooling water to the condenser, 'and resuming the supply of cooling water to the condenser responsiveto rise in temperature of a portion of the system affected by saiddiscontinuance of the water supply.

3f The method of refrigerating with a system having a cooling element and a water cooled condenser which includes, continuing circulation of refrigerant fluid in the system, and temporarily increasing the temperature of the cooling element to melt accumulated frost by discontinuingtheA -supply of cooling water to the condenser, and re suming the supplyof cooling water to the condenser responsive to rise intemperature of the cooling element.

4. In the method of refrgerating with a system comprising a generator, condenser,v evaporator. and absorber connected for the circulation of a cooling fluid, continuously cooling said absorber, cooling said condenser, and intermittently raising the temperature of the evaporator to melt accumulated frost by intermittently interrupting cooling of said condenser'.

5. A refrigerating system comprising' a generator, condenser, evaporator, and absorber connected for the circulationof a cooling fluid, a cooling water circuit inheat exchange relation with said absorber and condenser,V a'ndmeans for controlling the iiow of water in the portion of said circuit in heat exchange relation with the condenser, said means being manually operable to out off flow through said portion and automatically operable responsive to a predetermined rise in temperature in a part of the system to resume flow through said'portion.

6. A refrigerating system comprising a generator, condenser, evaporator, and absorber connected for the circulation of a cooling uid, and means for continuously cooling said absorber and intermittently cooling said'condenser including control means both manually operable and automatically operable responsive to rise in temperature of said evaporator.

7. A refrigerating system comprising a generator, condenser, evaporator, and absorber connected for the circulation of a cooling fluid, a cooling water circuit having a portion in heat exchange relation with said absorber, a portion in heat exchange relation with said condenser, and a by-pass portion around the latter, and a twoway valve in said circuit for directing water through the condenser cooling portion in one positon and the by-pass portion in the other position.

8. A refrigerating system comprising a gen-V erator, condenser, evaporator, and absorber con- 'nected for the circulation of a cooling fluid, a

cooling water circuit having a portion in heat exchange relation with said absorber, a portion in heat exchange relation with sa'id condenser, and a by-pass portion around the latter, a valve in said circuit for directing water through the condenser cooling portion in a rst position and through said by-pass portion in a second position, and means manually operable to shift the 'valve from said rst to second positions and automatically operable responsive to predetermined rise in temperature of a part of the refrigerating system for returning Vsaid valveto the first position.

9 A refrigerating system comprisng a generator, condenser, evaporator, and absorber connected for the circulation of acooling fluid, means for continuously cooling said absorber, means for cooling said condenser, manually operable means for interrupting the operation-,of said condenser cooling means, and means to resume operation of said condenser cooling means responsive to a -rating the condensate by Vdiffusion into an inert gas, absorbing refrigerant vapor from the resulting gas mixture into absorption liquid. from which refrigerant was previously expelle continuously removing the heat of absorption, and

intermittently interrupting said cooling of expelled vapor `to temporarily interrupt evaporation predetermined rise in temperatureof said evapoof refrigerant into the inert gas to cause rise in temperature in this part of thefsystem.

11. The process of refrigerating which comprises continuously expelling refrigerant' vapor yrefrigerant into the inert gas causing a rise in temperature of this part of the system, and resuming cooling of expelled vapor upon a predetermined rise in temperature.

12. A refrigerating system comprisinga generator andy an absorber interconnected for the circulation of absorption liquid therebetween, an evaporator having a refrigerant liquid inlet and interconnected with said absorber for the circulation of an inert gas therebetween, a first condenser extending below said evaporator inlet and connected from the lower end thereto, a liquid trap overflow conduit for liquid from said condenser to the generator at a level below said evaporator inlet, a second condenser above the level of said overflow and connected between the first said condenser and the vapor space of said generator, and means for alternately cooling said condensers.

13. A-'refrigerating system comprising a generator and an absorber interconnected for the circulation of an absorption liquid therebetween, an evaporator having a refrigerant Aliquid inlet and interconnectedl with said absorber for the circulation of inert gas therebetween, a condenser extendingbelow said evaporator inlet and connected thereto, a liquid trap overflow conduit for liquid from said condenser at a level below nately cooling said condenser and last `said conduit.

14. A refrigerating System comprisng a gen- .erator and an absorber interconnected for the circulation of absorption liquid therebetween, an evaporator having a refrigerant liquid inlet and interconnected with said absorber for the circulation of inert gas therebetween, a condenser extending below said evaporator inlet and connected thereto, a liquid trap overflow conduit for liquid from said condenser at a level below said evaporator inlet, a conduit for vapor from said generator to Asaid condenser having an enlarged chamber above the level of said overflow, land means for alternately cooling said condenser and last said conduit.

15. A refrigerating system comprising a generator and an absorber interconnected for the circulation of absorption liquid therebetween, an evaporator having a refrigerant liquid inlet and interconnected with said absorber for the circulation of inert gas therebetween, a first condenser extending below said evaporator inlet and connected from the lower end thereto, a vent conduitfrom the lowerend of said condenser extending above said evaporator liquid inlet and lconnected to the inert gas circuit, a liquid trap overiiow conduit for liquid from said condenserY and means for alternately cooling said condensers.

16. A refrigerating system comprising a generator and an absorber interconnected for the circulation of absorption liquid therebetween, an evaporator having a refrigerant liquid inlet and interconnected with said absorber for the circulation of an inert gas therebetween, a rst condenser extending below said evaporator inlet and connected from the lower end thereto, a liquid .trap o'verow conduit for liquid from said condenser to the generator at a. level below said evaporator inlet, a second condenser above the level of said overflow and connected between the rst said condenser and the vapor space of said generator, and means for alternately cooling said condensers, said means being manually directed to cool the upper condenser and automatically directed to cool the lower condenser responsive to a predetermined rise in temperature of saidv evaporator.

17. A refrigerating system comprising a generator and an absorber interconnected for kthe circulation of absorption liquid therebetween,v an evaporator having arefrigerant liquid inlet and interconnected with said absorber for the circulation of an inert gas therebetween, a rst con. denser extending below said evaporatorinlet and connected from the lower end thereto, a liquid trap overflow conduit for liquid from said condenser to the generator at a level below said evaporator inlet, a second condenser above the level of said overflow and connected between the rst said condenser and the vapor space of said generator, a cooling water supply circuit for said condensers, and a water switch valve in said circuit operative to direct cooling water alternately through said condensers.

18. A refrigerating system comprising a generator and an absorber interconnected for the circulation of absorption liquid therebetween, an evaporator having a refrigerant liquid inlet and interconnected with said absorberlfor the circula.- tion of an inert gas therebetween, a ,first condenser extending below said evaporator inlet and connected from the lower end thereto, a liquid trap overow conduit for liquid from said condenser to the generator at a level below said evaporator inlet, a second condenser above the level of said overflow and connected between the first said condenser and the vapor space of said generator, a cooling water supply circuit for said condensers, a water switch valve lin said circuit adapted to direct cooling water through saidld lower condenser in its normal position and through said upper condenser in its operated position, manually operatedv means for changing said valveto its operated position, and automatic means for returning said valve to its normalposition responsive to a predetermined rise in temperature of said evaporator.

19. Arefrigerating system comprising a generatoradaptedY tocolrtain a solution of refrigerant in an absorption liquid, an absorber, means for circulating absorption liquid from said generator through said absorber, an evaporator interconnected with'said absorber for the circulation-of an inert gas therebetween, a condenser connected to receive vapor from said generator and discharge liquid into said evaporator, a gas trap vent from said condenser to said evaporator, a cooling water circuit for cooling said absorber Y and condenser in series, a by-pass conduit around the condenser portion of said cooling watercircuit, and a water switch valve for directing cool- 'the circulation of an inert gas therebetween, a

condenser connected to receive vapor from said generator, a liquid trap overflow conduit from said condenser to said evaporator, a gas trap vent around said liquid trap, a cooling Water circuit having a portion in heat exchange relation with said absorber and another portion in heat exchange relation with said condenser, a by-pass conduit around the condenser portion of said cooling circuit, and means for normally directing the cooling water through said condenser portion said means being manually operable to direct cooling water'through said by-pass and automatically operable to be returned to its normal positionjresponsiveito a predetermined rise in temperature of said evaporator.

21. The method of refrigeration with a system having a cooling element and a heat rejecting portion which includes, continuing circulation.

of refrigerant fluid in the system, and temporarily raising the temperature of the cooling element to melt accumulated frost by decreasing removal of heat from the heat rejecting portion of the system and increasing the cooling of said portion responsive to predetermined rise in temperature of said cooling element.

22. In the method of refrigeration by circulation of a cooling fluid through a cycle of evaporation at a low temperature and condensation at a higher temperature, removing heat of condensa- Y tion by transfer to `a 4second cooling fluid, and intermittently raising said low temperature with continuing circulation of said rst cooling fluid by intermittently decreasing heat transfer to said second cooling fluid.

23. In the method of refrigeration by circulation of a cooling uid through a cycle of evaporation at a low temperature and condensation at a higher temperature, removing heat of condnsation by transfer to a` second cooling fluid, and temporarily raising said low temperature with continuing circulation of said first cooling fluid by decreasing heat transfer to said second cooling fluid and increasing the heat transfer responsive to a predetermined rise of said temperature.

DONALD iaRANCH KNIGHT. 

